Technical Field
The present disclosure relates to integrated circuits (ICs) with interface liners adjacent to conductive contacts, and more specifically, to IC structures with interface liners which include metal compounds diffused from a doped metal contact, and methods of forming the same.
Related Art
Each IC can be made up of billions of interconnected devices, such as transistors, resistors, capacitors, and diodes, located on one or more chips of semiconductor substrate material. The quality and viability of a product including an IC can be at least partially dependent on the techniques used for fabricating the IC and the structure of various components therein. Fabrication of an IC can include two phases: front-end-of-line processes (FEOL) and back-end-of-line processes (BEOL). FEOL generally includes fabrication processes performed on a wafer up to and including the formation of a first “metal level,” i.e., a metal wire for connecting several semiconductor devices together. In the case of a transistor, a group of vertically-extending conductive contacts can provide electrical connections to the transistor from other functional elements of a circuit. BEOL generally includes fabrication processes following the formation of the first metal level, including the formation of all subsequent metal levels. Each metal level can include metal wires therein, which can be connected to other metal levels through vertically-oriented conducting wires known as vias. In conventional BEOL processing, a layer of vias is formed to connected devices in an IC structure to a layer of metal wires formed on top of the vias, with a successive layer of vias formed thereon, followed by another layer of meal wires, etc. To provide greater scaling and sophistication of the fabricated device, the number of metal levels can be varied to suit a particular application, e.g., by providing four to six metal levels, or as many as, in a further example, sixteen or more metal levels.
Conductive contacts extending between levels, or similar structures such as vias, may be fabricated to include additional materials for providing separation between conductive metals and insulating materials in the IC structure. Both contacts and vias are referred to collectively herein by use of the terms “contact,” “metal contact,” and/or “conductive contact.” In conventional processing, such structures may include refractory metal liners formed on sidewalls of an opening in which metal contacts are formed. Refractory metal liners can prevent electromigration of conductive materials into adjacent portions of the IC structure. Although refractory metal liners have proven satisfactory for such purposes, conventional formation of such materials may require forming additional materials and/or removing portions thereof in additional process steps, which may increase the time and costs to manufacture a product. Despite these contributions to time and cost, removing refractory metal liners from a circuit structure has proven unsatisfactory for maintaining the quality and intended functions in an IC structure fabricated with conventional techniques.